Improving Fuel Cells for Cars
A new method for making materials just a few atoms thick could pave the way to automotive fuel cells that use readily available fuels instead of hydrogen, which is difficult to produce and store. The new fuel cells would be smaller, lower-temperature versions of solid-oxide fuel cells (SOFCs), which were originally developed for use in stationary applications such as power plants. Startup Sienergy Systems, based in Quincy, MA, was founded to bring the fuel cells to market. Last week the company announced half a million dollars in early-stage funding.
The synthesis method, developed by Harvard professor of materials science Shriram Ramanathan, produces high-quality solid-oxide electrolytes that are about 25 nanometers thick--about a thousandth the thickness of the electrolytes used in conventional SOFCs. The thinner electrolyte allows the fuel cells to run at about 300 ºC--much cooler than the 800 to 1,000 degrees typical for SOFCs. The lower temperatures could lead to lower costs and make it much easier to package the fuel cells for use in vehicles and portable generators.
Several major automakers are developing fuel cells, but they're proton-exchange-membrane fuel cells that can run only on hydrogen, says Harry Tuller, a professor of ceramics and electronic materials at MIT who is also developing lower-temperature SOFCs. Hydrogen has a number of drawbacks. It must be derived from sources such as natural gas or water, a process that consumes energy and typically releases carbon dioxide. What's more, it's a diffuse gas that's difficult to store, and there isn't an extensive infrastructure for delivering it.
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